Mass Effect's Interactive Comic walkthrough •
Page 8

After a pitched battle with hundreds of drones, you have the Rachni Queen at your mercy. She pledges to peacefully go on her way should you release her, but factoring in the violent history of the race, you kill her instead.

Mass Effect Comic: Decision 2, Kill Rachni Queen

"Wrex wanted the Genophage cure for his people. I tried to convince him to help me destroy it, that these Krogan weren't real. But he wouldn't back down..."